Think it is a tolerance build up requiring more of the drug to obtain the desired effect. Some build up an incredible tolerance that would kill others at a fraction of the dose.
Same thing with booze. How idiotic it was to obtain the volume of these pills people once could; or tolerate taking dozens of them a day. To get a script now is tough after an inquisition from the doc being a possible drug-addict. Posted earlier, when I took them no more than 4 in a day, couldn’t dump for a week, even taking laxatives. Then when I finally could, felt like I was passing a full-size sedan. This was enough to seriously limit my intake, lol.
And people who buy drugs, any of them, off the street, have to be brain dead, having NO idea what’s in them: Comet cleanser, flour, airplane glue, oh and a killer-dose of fentanyl that is the size of a pencil tip? Geezuz.